Stacked laminate mold and method of making

ABSTRACT

A method of forming a stacked laminate mold. The method comprises the steps of: a) orienting a plurality of plates to have their respective major planes at a first angle relative to a fixed reference plane and parallel to one another, each of the plates including opposed parallel first and second major surfaces defining therebetween the major plane of each of the plurality of plates, each of the plates further including a mold surface connecting the first and second major surfaces; b) forming a groove in the plurality of plates, the groove including a groove surface defined by cylindric surface that is the construct of translating a two-dimensional groove profile through the plate along a line that is oblique to at least one of the plate major surface and the plate mold surface, and wherein the groove surface intersects each respective plate first major surface and each respective plate mold surface; and thereafter c) reorienting the plates to have their respective major planes at a second angle relative to the reference for molding. Also disclosed is a stacked laminate mold. The mold comprises a plurality of plates, each of the plates including: opposed parallel first and second major surfaces defining therebetween a major plane of each of the plurality of plates; a mold surface connecting the first and second major surfaces; and a plurality of cavities in each of the plurality of plates. Each of the cavities is open at least to the mold surface and includes a cavity surface defined by cylindric surface that is the construct of translating a two-dimensional cavity profile through the plate along a line that is oblique to at least one of the plate major surface and the plate minor surface, and the cavity surface intersects each respective plate first major surface and each respective plate mold surface. The first major surface of a first one of the plurality of plates is adjacent the second major surface of a second one of the plurality of plates.

TECHNICAL FIELD

The present invention relates generally to methods of forming a mold andto such a mold, and more particularly to methods of forming stackedlaminate molds and to such stacked laminate molds.

BACKGROUND OF THE INVENTION

Stacked laminate molds and their use are known. In one known mold, aplurality of plates can be formed having V-shaped grooves cut through atop edge of the plate with the V-shaped groove extending from a firstsurface to a second surface of the plate with the bottom of the groovebeing parallel to the top surface of the plate. Adjacent plates may bestaggered such that the grooves in one plate are bounded by the majorsurfaces of the plates in front and in back of such plate. Such plateshave been known to be used, for example, for forming molded piledproducts. One example of a stacked laminate mold is taught in U.S. Pat.No. 3,312,583, "Apertured and Staggered Molded Piled Product" (Rochlis).

It has also been known to use stacked laminate molds for making the hookcomponent of hook-and-loop fasteners. In such molds, it is known to formcomplex hook-shaped engaging members with a stacked laminate mold byetching or engraving a cavity into a major surface of a mold plate, thecavity having the desired hook configuration such as a J-hook or nailheaded hook member. The cavity is open to the top surface of the stackedlaminate mold. A plurality of such hooks can be formed across the lengthof one mold plate, with a plurality of similarly configured mold platesplaced adjacent to one another. All of the plates may include cavities,or spacer plates without cavities may be placed between plates withcavities. Such stacked laminate molds can be used for batch production,that is for making discrete lengths and widths of molded products havinga plurality of hooks. See for example U.S. Pat. Nos. 3,147,528,"Separable Fastener Element" (Erb); and 5,368,549, "Method forInjection-Molding an Orthopedic Device and Product of the Method"(McVicker). It is also known to use circular-shaped stacked laminatemolds for continuous production of molded strips having a plurality ofhooks. See for example U.S. Pat. Nos. 3,762,000, "Production of aContinuous Molded Plastic Strip" (Menzin et al.); 3,196,490, "Apparatusfor Manufacture of a Continuous Strip of Molded Plastic Product" (Erb);and 4,872,243, "Multi-Hook Fastener Member" (Fischer); and Rosato andRosato, Injection Molding Handbook, VanNostrand Reinhold Company, pp.753-56.

It has also been known to use stacked laminate molds in the productionof retroreflective or triple-reflective material. The stacked laminatesare generally configured so as to form three full surfaces of a cubewhen the adjacent plates are stacked together for molding theretroreflective product. See for example U.S. Pat. Nos. 1,591,572,"Process and Apparatus for Making Central Triple Reflectors" (Stimson);3,649,153, "Faceted Core" (Brudy); 4,066,236, "Cube Comer TypeRetroreflector Bodies and Molds Made Therewith" (Lindner); and4,095,773, "Subassemblies for Cube Comer Type Retroreflector Molds"(Lindner); and German Provisional Publication (OS) 42 36 799 A1(Gubela).

Methods for forming an electrically conductive coating on non-conductivemold surfaces are known, as are methods for electrodepositing a metalcoating onto a mold surface. See for example U.S. Pat. Nos. 4,871,623,"Sheet-Member Containing a Plurality of Elongated EnclosedElectrodeposited Channels and Method" (Hoopman et al.); and 5,070,606,"Method for Producing a Sheet Member Containing at Least One EnclosedChannel" (Hoopman et al.)

SUMMARY OF THE INVENTION

The present invention presents a stacked laminate mold, and methods ofmaking stacked laminate molds. Such a stacked laminate mold may be usedto mold a desired article or may be used to mold a subsequent mold. Whenthe stacked laminate mold is used to mold a subsequent mold, an inverseof the stacked laminate mold can be made, for example, byelectrodepositing a metal coating on the stacked laminate mold andremoving the metal inverse from the stacked laminate mold. This metalinverse can be used to mold a desired article, or may itself be anintermediate mold. When the metal inverse is an intermediate mold, it ispossible to form an inverse of the metal inverse to obtain a mold thatis a replicate of the mold surface of the stacked laminate mold. Such areplicate can comprise, for example, an electrodeposited mold, a plasticmold, a silicone mold, or any other desired material.

In one preferred embodiment of the present invention, a stacked laminatemold is formed having cavities that are the inverse of the desired finalarticle. Such a mold may be referred to as a "negative" mold, as itsconfiguration is the negative of the final desired article. The stackedlaminate negative is then used to produce a metal "positive" mold byelectrodepositing a metal coating, such as nickel, onto the stackedlaminate negative. This metal positive has a mold surface that is thesame as, in other words a "positive" of, the surface of the finaldesired article. This metal positive is then used to form a "negative"mold that is a replicate of the original stacked laminate mold, having aconfiguration that is a negative of the final desired article. Thisnegative mold can comprise any desired material, such as a suitableplastic or silicone composition. This final negative mold can then beused to form the final desired article. In one preferred embodiment, themolded article comprises a generally planar base sheet having aplurality of protrusions extending therefrom, the protrusions beingformed by the cavities in the mold.

While the above-described system is a preferred embodiment, it isunderstood that the stacked laminate mold may be used to directly mold adesired article, or that any number of intermediate molds may be made onthe way to molding the ultimate desired molded article. In that regard,it is understood that the stacked laminate mold may be either a negativeor positive of the final desired article.

The stacked laminate mold of the present invention is made by a methodwhich provides a convenient and accurate way of forming mold cavitieshaving accurately controlled surfaces, and edges between surfaces thatclosely approach a true linear edge. This accuracy can be replicated inthe subsequent intermediate molds and in the final molded article.

One preferred embodiment of the present invention presents a method offorming a stacked laminate mold. The method comprises the steps of: a)orienting a plurality of plates to have their respective major planes ata first angle relative to a fixed reference plane and parallel to oneanother, each of the plates including opposed parallel first and secondmajor surfaces defining therebetween the major plane of each of theplurality of plates, each of the plates further including a mold surfaceconnecting the first and second major surfaces; b) forming a groove inthe plurality of plates, the groove including a groove surface definedby cylindric surface that is the construct of translating atwo-dimensional groove profile through the plate along a line that isoblique to at least one of the plate major surface and the plate moldsurface, and wherein the groove surface intersects each respective platefirst major surface and each respective plate mold surface; andthereafter c) reorienting the plates to have their respective majorplanes at a second angle relative to the reference for molding.

In one preferred embodiment of the above method, upon performing stepc), a plurality of mold cavities are provided, each of the mold cavitiesbeing open at the mold surface of the plates and being bounded at leastby: i) a first cavity surface formed by the groove surface; and ii) asecond cavity surface defined by the second major surface of a secondone of the plurality of plates adjacent to the first major surface ofthe first plate.

In another preferred embodiment of the above method, the groove surfacefurther intersects the plate second major surface.

In another preferred embodiment of the above method, the mold surfacesof the plurality of plates are coplanar upon performing step c). Inanother preferred embodiment, the mold surface of each of the plates isperpendicular to the respective first and second major surfaces of eachplate.

In another preferred embodiment of the above method, step b) comprisesforming a groove including a planar first groove surface, a planarsecond groove surface, and a base joining the first and second groovesurfaces, wherein the first groove surface intersects each respectiveplate first major surface and each respective plate mold surface,wherein the second groove surface intersects each respective plate firstmajor surface and each respective plate mold surface, and wherein thebase is oblique relative to at least one of the major plane and the moldsurface. In another embodiment, the first and second groove surfacesfurther intersect the plate second major surface. In another embodiment,the first and second groove surfaces intersect so as to form a lineargroove base.

In another preferred embodiment of the above method, step b) comprisesforming a plurality of grooves. This embodiment can further include thestep of: d) moving a first one of the plurality of plates relative to asecond and a third plate each adjacent the first plate, such that acavity in the first plate formed by a first of the plurality of groovesis offset from cavities formed by the first groove in the second andthird plates.

In another preferred embodiment, the above method includes the furtherstep of: d) subsequent to step b), inserting a plurality of spacers intothe mold such that a respective one of the plurality of spacers isadjacent a respective one of the plurality of plates, wherein eachrespective spacer overlays at least that portion of the first majorsurface of each respective plate intersected by the first and secondgroove surfaces.

Another preferred embodiment of the present invention presents a stackedlaminate mold. The mold comprises a plurality of plates, each of theplates including: opposed parallel first and second major surfacesdefining therebetween a major plane of each of the plurality of plates;a mold surface connecting the first and second major surfaces; and aplurality of cavities in each of the plurality of plates. Each of thecavities is open at least to the mold surface and includes a cavitysurface defined by cylindric surface that is the construct oftranslating a two-dimensional cavity profile through the plate along aline that is oblique to at least one of the plate major surface and theplate minor surface, and the cavity surface intersects each respectiveplate first major surface and each respective plate mold surface. Thefirst major surface of a first one of the plurality of plates isadjacent the second major surface of a second one of the plurality ofplates.

In one preferred embodiment of the above mold, each of the mold cavitiesare open at the mold surface of the plates and are bounded at least by:i) a first cavity surface formed by the cavity surface; and ii) a secondcavity surface defined by the second major surface of a second one ofthe plurality of plates adjacent to the first major surface of the firstplate.

In another preferred embodiment of the above mold, the mold surfaces ofeach of the plurality of plates are coplanar. In another preferredembodiment of the mold, the mold surfaces of each of the plates isperpendicular to the respective first and second major surfaces of eachplate.

In another preferred embodiment of the mold, the cavity surface includesa planar first cavity surface, a planar second cavity surface, and abase joining the first and second cavity surfaces. The first cavitysurface intersects each respective plate first major surface and eachrespective plate mold surface, the second cavity surface intersects eachrespective plate first major surface and each respective plate moldsurface, and the base is oblique relative to at least one of the majorplane and the mold surface. In one preferred embodiment of this mold,the first and second cavity surfaces intersect so as to form a linearcavity base. In another preferred embodiment, the first and secondcavity surfaces further intersect the plate second major surface.

In another preferred embodiment of the above mold, the mold furthercomprises a plurality of spacers. A respective one of the plurality ofspacers is adjacent a respective one of the plurality of plates and eachrespective spacer overlays at least that portion of the first majorsurface of each respective plate intersected by the first and secondcavity surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to theappended Figures, wherein like structure is referred to by like numeralsthroughout the several views, and wherein:

FIG. 1 is a side view of a plurality of plates according to the presentinvention, prior to forming a groove in the plates;

FIG. 2 is a top view of the plates of FIG. 1;

FIG. 3 is a side view of the stacked laminate mold of FIG. 1, in whichthe plates have been oriented at a first orientation and have had agroove formed therein;

FIG. 4 is a top view of the stacked laminate mold of FIG. 3;

FIG. 5 is a plan view taken along line 5--5 of FIG. 3 of a single plateof the stacked laminate mold with a single groove formed therein;

FIG. 6 is an isometric view of a the plate of FIG. 5;

FIG. 7 is an isometric view of two adjacent plates of the mold of FIG.3, oriented at a second angle;

FIG. 8 is a view like FIG. 6 illustrating a second embodiment of thepresent invention;

FIG. 9 is a view like FIG. 7 of the second embodiment;

FIG. 10 is a top view of the stacked laminate mold of FIG. 3, with theplates oriented at a second angle and with a plurality of grooves formedtherein, with the plates aligned along a first end thereof;

FIG. 11 is a view like FIG. 10, with the plates aligned along a secondend thereof;

FIG. 12 is a side elevational view of a single point milling machinecutter useful in making the stacked laminate mold of FIG. 3;

FIG. 13 is a front elevational view of the cutter of FIG. 12;

FIG. 14 is a bottom end view of the milling machine cutter of FIG. 12;

FIG. 15 is an isometric view of a frame holding a plurality of plates ofFIG. 3; and

FIG. 16 is a view like FIG. 5 showing alternate embodiments of groovesaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of the stacked laminate mold according to the presentinvention will now be described along with a preferred method of makingsuch a mold. FIG. 1 is a side view of a plurality of plates 12 accordingto the present invention, prior to forming a groove in the plates tomake the stacked laminate mold 10. Each plate 12 includes a first majorsurface 14 and a second major surface 16. A plurality of the plates 12are stacked adjacent to one another such that the first major surface 14of one plate 12 is adjacent the second major surface 16 of an adjacentplate 12. Each plate 12 also includes a mold surface 18. As seen in FIG.2, which is a top view of the stacked plates of FIG. 1, each plate 12also includes a first edge 20 and second edge 22 at the intersection ofmold surface 18 with first major surface 14 and second major surface 16,respectively. Each plate 12 also includes a first end 24 and a secondend 26. In one preferred embodiment, each plate 12 is a regularrectangular solid with first and second major surfaces 14 and 16 beingparallel to one another and of the same size, with first end 24 andsecond end 26 being parallel to one another and of the same size, andwith mold surface 18 joining the top edges of first and second majorsurfaces 14 and 16 and first and second ends 24 and 26 at a right angle.Each of the plates 12 may be of identical size and configuration or, inthe preferred mode as illustrated, alternating plates may be ofdifferent length such that there is a first group of plates each havinga shorter first length and a second group of plates each having a longersecond length with the plates 12 arranged so as to alternate the longand short plates. Each of the plates 12 includes a major plane 28 whichis parallel to and between the first and second major surfaces 14 and16. Each plate 12 further includes a minor plane 30 defined by the planeof the mold surface 18. As seen in FIG. 1, the mold surfaces 18 of thestack of plates 12 should be carefully formed so as to present acontinuous, uninterrupted surface made up of each of the individual moldsurfaces 18.

Formation of the cavities in the stacked laminate mold proceeds asfollows according to a first preferred embodiment. The plates 12 areprovided in a suitable frame 80 (see FIG. 15) to secure all of theplates together such that the major plane 28 of each plate is at anincline angle a relative to a reference plane R as illustrated in FIG.3. Frame 80 includes base 82 to which are affixed incline blocks 84 and86 form orienting plates 12 at angle α. Frame 80 also includes crossbars88 for securing the plates 12 in place. Holes 90 are provided in base 82to aid in securing the frame 10 while forming grooves in the plates 12.Angle α is some angle different from angle β at which the plates providea continuous mold surface comprising each of the individual moldsurfaces 18. As seen in FIG. 4, the plates 12 have been held in placesuch that each of the first ends 24 are coplanar. With the plates heldat angle α, groove 40 is then formed through the mold surface 18 andfirst major surface 14 of each plate 12. In one preferred embodiment,groove 14 extends parallel to plane R so as to form individual groovesegments of equal depth in each of the plates 12. It is also within thescope of the present invention to form the groove 40 non-parallel toplane R such that the groove depth varies from plate to plate.

In one preferred embodiment illustrated in FIGS. 4 and 5, groove 40 is aV-shaped groove comprising first and second planar surfaces 42 and 44meeting at base 46, which in this embodiment is a line at 46. FIGS.12-14 illustrate a preferred embodiment of a single point millingmachine cutter useful in cutting V-shaped groove 40. The single pointmilling machine cutter 70 includes a cylindrical shaft 72 suitable formounting in known milling machines. At one end of the shaft 72 is aworking end 73 for cutting the groove 40. Working end 73 includes astraight cutting edge 74 formed at the intersection of a tapered surface78 with a recessed surface 76 as seen in FIGS. 12 and 13. The millingmachine cutter 70 is rotated in direction B as it is traversed relativeto the plurality of plates 12 for forming the groove 40. Angle (a) isthe included angle between the cutting edge 74 and the longitudinal axisof the cutter 70. Angle (a) will define the included angle of theV-shaped groove 40, that is the included angle of the groove 40 will betwice angle (a). Both the tapered surface 78 and the edge of the toolopposite the cutting edge 74 can preferably include a back taper orclearance taper as is known in the art. Other tools can also be used incutting groove 40, including, for example, square end or round endmilling machine cutters, a suitably tapered cutting or grinding wheel,or the like. In one preferred embodiment, the tool is translatedrelative to the plates along a line that lies in a plane that isperpendicular to the plate major plane 28 as illustrated in FIGS. 4-11.The tool may instead be translated along a line that lies in a planeoblique to the plate major plane 28.

To further illustrate the configuration of the cavities formed in thestacked laminate mold 10 by forming a V-shaped groove 40, a single plate12 is illustrated in FIG. 6. It is seen that groove surfaces 42 and 44meet at linear groove base 46. In the illustrated embodiment, firstgroove surface 42 intersects the plate first major surface 14 at firstrear edge 48 and intersects mold surface 18 at first top edge 52.Similarly, second groove surface 44 intersects the plate mold surface 18at second top edge 54 and intersects the first major surface 14 atsecond rear edge 50. Groove base 46 extends from first major surface 14to mold surface 18. Groove surfaces 42 and 44 may extend to second edge22 of the mold surface 18 as illustrated, or may terminate some distanceaway from second edge 22.

The term "groove surface" is generally used when discussing theconfiguration of the groove formed in the plurality of plates 12, andthe term "cavity surface" is generally used to describe those groovesurfaces when the plates 12 are configured to form a mold. However, theterms "groove surface" and "cavity surface" are interchangeablethroughout.

FIG. 7 illustrates two adjacent plates 12 returned to incline angle βwhich positions the plurality of plates into a molding position. Inclineangle β is that orientation at which the mold surfaces 18 of each of theplates 12 form a continuous, coplanar mold surface of the stackedlaminate mold 10. It is seen that pyramidal cavities are formed by theV-shaped grooves, each individual cavity being bounded by first cavitysurface 42 and second cavity surface 44 of one of the plates 12, and bya third cavity surface formed by a portion of the second major surface16 of an adjacent plate 12. Such a cavity is used to mold atriangular-based pyramidal protrusion. For clarity, only two plates 12are illustrated in FIG. 7; however, it is understood that any number ofplates 12 may be combined together to form the grooves in the plates atfirst incline angle a and to form the mold 10 at the second inclineangle β.

In one preferred embodiment, a plurality of parallel grooves 40 areformed through each of the plates 12 while they are oriented in theirgroove-forming orientation at angle α. Upon returning the plates totheir second, mold-forming orientation at angle β, this will result in aplurality of triangular-based cavities as illustrated in FIG. 10. It isalso within the scope of the present invention to form a plurality ofgrooves not parallel to one another. In one preferred embodiment, angleβ is 90° relative to reference plane R, and angle α is 45° relative toplane R. It is also within the scope of the present invention for themold forming orientation at angle β to be less than or greater than 90°.Preferably, mold surfaces 18 of each plate are formed to be continuousand coplanar when the plates 12 are at angle β. Such an arrangement willallow the final molded article to have a generally planar base with theprotrusions extending from the planar base. However, for certainapplications it may be desirable that the final molded article have agrooved base with protrusions extending therefrom. In such anarrangement, the individual mold surfaces 18 need not be continuous andcoplanar when the plates are at mold forming angle β. As to grooveforming orientation angle α, it can be greater than or less than angleβ. In other words, the plates may be tilted in either direction fromangle β during formation of the groove. It is also within the scope ofthe present invention to form one or more grooves with the plates heldat a first angle α and then form one or more grooves with the platesheld at a second angle α so as to form different configurations of thecavities within a single stacked laminate mold 10.

An alternate embodiment of the V-shaped groove 40 is illustrated inFIGS. 8 and 9. FIG. 8 illustrates a single plate; however, it isunderstood that this groove can be advantageously formed by cuttingthrough a plurality of plates 12 as explained with respect to FIGS. 3and 4. In the embodiment illustrated in FIG. 8, the first and secondgroove surfaces are cut deep enough into the plate 12 such that firstgroove or cavity surface 42 intersects the plate mold surface 18 atfirst top edge 52, first major surface 14 at first rear edge 48, andsecond major surface 16 at first forward edge 56. Similarly, secondgroove surface 44 intersects the plate mold surface 18 at second topedge 54, first major surface 14 at second rear edge 50, and second majorsurface 16 at second forward edge 58. With such a groove, the groovebase 46 extends from the first major surface 14 to the second majorsurface 16. Preferably, groove base 46 is oblique to the mold surface18; however, it is also within the scope of the present invention forthe groove base 46 to be parallel to mold surface 18.

An individual cavity formed by the groove of FIG. 8 is illustrated withrespect to FIG. 9. For illustrative purposes, FIG. 9 illustrates plate12 having groove 40 formed therein, with plate 12 being between twooptional spacer plates 12' not having a groove formed therein. It isunderstood that adjacent plates 12 may each have cavities formed thereinif spacer plates 12' are not used. It is seen that the cavity of thesecond embodiment is bounded by the first cavity surface 42, secondcavity surface 44, a third cavity surface formed by a portion of thesecond major surface 16 of the plate immediately behind plate 12, and afourth cavity surface formed by a portion of the first major surface 14of the plate immediately in front of plate 12. Such a cavity is used tomold a protrusion having a four-sided base.

As seen in FIG. 10, each of the plates 12 can be oriented such thatfirst ends 24 are coplanar during the groove-forming process at angle αand upon returning the plates to their mold-forming orientation at angleβ. Accordingly, rows of cavities in adjacent plates 12 are in linerelative to one another in direction A. This can be seen by noting thatthe groove base line 46 of a cavity in one plate is aligned with thegroove base 46 of the cavities immediately behind and in front eachrespective cavity. In one preferred embodiment, adjacent grooves 40 areformed such that the widest portion of the cavity at the intersection ofthe cavity with first surface 14 is touching or nearly touching thewidest portion of the cavity adjacent to that on the same plate 12. Itis also within the scope of the invention that adjacent cavities withina single plate 12 may be spaced as far apart from one another asdesired.

FIG. 11 illustrates a convenient and simple means for staggering thecavities in adjacent plates 12 so that the cavities in adjacent platesare not in line in direction A. In FIG. 11, the plates have beenoriented such that each of the first ends 24 are coplanar duringmachining as described above and then reoriented such that each of thesecond ends 26 are coplanar when the plates are held in theirmold-forming orientation at incline β. In one preferred embodiment, thedifference in length between the longer plates and the shorter plates isequal to one half the pitch of adjacent grooves 40. Upon aligning theplates at second end 26, the cavities in one plate will be betweencavities in an adjacent plate 12 as illustrated in FIG. 11. By varyingthe lengths of the plates and aligning first ends 24 during grooveforming and the second ends 26 during mold formation, it is possible toarrange grooves in adjacent plates in any desired pattern. In additionto having the length difference being one half the pitch of adjacentgrooves, it is also possible to use any other difference in length.Furthermore, it is possible to progressively increase the length of two,three, four, or any number of adjacent plates so as to stagger the arrayof cavities in groups of two, three, four, or more plates.

In another preferred embodiment, the cavities 40 may be formed in asingle plate at a time, rather than by cutting a groove through aplurality of plates as described above. In this alternate embodiment, itis possible to form a plurality of cavities 40 in at least the moldsurface 18 and first major surface 14 in one plate at a time, by any ofa variety of means. Such cavities can be formed with a single pointmilling machine cutter 70 described above, or with any suitable grindingor cutting wheel, for example. It is also possible to stamp individualplates 12 with the desired cavity arrangements, or to mold individualplates having the individual cavities. It is also possible to etch orengrave each of the cavities 40 in plate 12 as is well known in the art.After forming a desired number of plates 12 by such a method, theplurality of plates could be assembled so as to form the stackedlaminate mold 10 as described above.

In another preferred embodiment, spacer plates 12' are inserted betweenplates 12. Spacer plates 12' do not have any cavities, and serve toenclose the cavities as described above with respect to the staggeredplates 12, and to separate rows of cavities 40 by any desired thicknessof the spacer plate 12. It is also within the scope of the presentinvention to take plates with different groove geometries formed by anyof the methods described herein and assembling these in any desiredpattern to provide a stacked laminate mold 10 having varying cavitygeometries. Such an arrangement can include discrete cavities ofdifferent configuration, or can be arranged such that cavities inadjacent plates combine to form a composite cavity. Composite cavitiescan be used to form composite protrusions that are a combination ofeither like or dissimilar individual protrusions.

In still another preferred embodiment, plates 12 are circular, ratherthan rectangular. In this embodiment, grooves 40 are formed in plates 12one plate at a time by any of the means described herein. A circularstacked laminate mold may be advantageously used in continuouslyprocessing a web form of a molded article rather than the batchprocessing used with the rectangular plates described above.

Other groove shapes are within the scope of the present invention. FIG.16 illustrates some of the many groove variations that fall within thescope of the present invention. For example, either or both of surfaces42 and 44 could be curvilinear or arcuate as opposed to planar, or cancomprise any desired number of discrete and adjacent planar andcurvilinear portions. Furthermore, rather than a V-shaped groove meetingat a line at base 46 as illustrated in FIGS. 5-11, groove base 46 coulditself be a surface. For example, groove 40a includes a planar groovebase 46 and groove 40b includes a curvilinear groove base 46 joining thefirst and second groove surfaces 42 and 44. It is also possible thatgroove surfaces 42 and 44 could together form a continuous surface asseen in groove 40c. As seen with respect to groove 40d, the groove cancomprise parallel and planar first and second surfaces 42 and 44 and anarcuate groove base 46 between the first and second surfaces. As seen ingroove 40e, the groove can comprise generally V-shaped first and secondsurfaces 42 and 44, joined by an arcuate groove base 46 which intersectsthe first and second surfaces at a discontinuity rather than smoothly.It is also possible for the groove to include any desired number ofsurfaces as illustrated with respect to groove 40f. For example, groove40f includes a plurality of planar first surfaces 42a, 42b, 42c, and 42dand a planar second surface 44 joined by an arcuate surface 46. It is tobe understood from the foregoing non-limiting examples that the profileof the groove 40 can be any desired shape. For grooves having a plane ofsymmetry at groove base 46, the grooves can be conveniently cut with asingle point milling machine cutter 70 having a cutting edge 74configured to produce the desired groove contour. Such grooves can beconveniently made either with the process described herein with respectto FIGS. 1-4 or by forming the plates one at a time by any other methoddescribed herein.

As illustrated in FIG. 16, groove 40 can be formed with a plate 12oriented at angle a such that the groove base 46 is oblique to the platemold surface 18. It is understood, of course, that the groove 40 canalso be parallel to plate mold surface 18 if the grooves are cut whilethe plates are held at angle β. When the groove base 46 is parallel tothe mold surface 18, the cavity formed is a portion of a cylindricsurface. As the term "cylindric surface" is used herein, it refers tothe surface generated by taking a two-dimensional region as illustratedby the groove contours 40 in FIGS. 5 and 16 and translating this regionalong a straight line through space. In one preferred embodiment, theline of translation lies in a plane perpendicular to plate major plane28. It is also within the scope of the present invention for the line oftranslation to lie in a plane oblique to plate major plane 28. Thecavity thus formed is analogous to a cylindric solid with the groovesurfaces being that portion of the cylindric surface included within theplate 12. The terms "cylindric surface" and "cylindric solid" are usedherein with respect to surfaces and regions bounded either by planarsurfaces or curvilinear surfaces. Orienting the plates at angle adifferent from angle β is a convenient means for forming cylindricsurfaces which are the construct of moving the region in a directionoblique to mold surface 18. Orienting plates 12 at angle α equal toangle β is a convenient means for translating the cylindric surface in adirection parallel to mold surface 18. It is also possible to formcavities which are a portion of a torus by revolving a two-dimensionalregion as illustrated by the groove contour in FIGS. 5 and 16 about anaxis which is eccentric to the region.

One embodiment of a stacked laminate mold can be made as follows. Eightyacrylic plates 12 are provided, each being 3.175 mm (0.125 in) thick,approximately 20.3 cm (8.0 in) long, and approximately 2.0 inches high.The plates then have 0.5 inch holes drilled through the major surfacesto allow the plates to be fixtured at orientation angle β of 90°relative to reference plane R. The bottom surface and mold surface 18 ofeach of the plates 12 in the assembled stack are then machined so as toprovide continuous, coplanar surfaces. The bottom surfaces of the platesare marked for reference, and the stack is disassembled. Forty of theplates 12 are then reassembled in a stack, and are machined to 20.3 cm(8.0 in) in length. The remaining forty plates 12 are reassembled andmachined to 20.19 cm (7.950 in) in length. The eighty plates 12 are thenreassembled with alternating long and short plates, with the first ends24 of each plate 12 coplanar, and with the plates held at orientationangle α of 45° relative to reference plane R. A plurality of parallelV-shaped grooves 40 are then machined into the mold surface 18 of theplurality of plates with a single point milling machine cutter 70 asdescribed above. The groove 40 has an included angle at the intersection46 of groove surface 42 and 44 of 68.6°, with the grooves atapproximately 2.54 mm (0.100 in) intervals across a 12.7 cm (5.0 in)width of the plates 12. The cavities formed when the plates are returnedto orientation angle β are configured for forming triangular-basedpyramid protrusions, have a maximum depth at the intersection of base 46with first major surface 14 of approximately 2.5 mm (0.100 in), a widthmeasured at first edge 20 of the mold surface 18 of approximately 2.3 mm(0.090 in), and extend to within approximately 0.5 mm (0.02 in) of thesecond edge 22 of mold surface 18. The plates 12 are then aligned so asto be coplanar at second end 26 to stagger the cavities in adjacentplates by an amount approximately equal to one-half the distance betweenadjacent cavities. In one preferred embodiment, the cavities have adepth of from 0.6 to 6.0 mm (0.024 to 0.24 in), a length of from 0.6 to6.0 mm (0.024 to 0.24 in), and a maximum width of from 0.6 to 6.0 mm(0.024 to 0.24 in), although larger and smaller cavities are also withinthe scope of the invention. With V-shaped grooves, the groove surfacespreferably have an included angle of from 20 to 160°.

The plates 12 of the stacked laminate mold 10 may be constructed of aconductive material such as nickel or brass, or alternatively, by anon-conductive material having a conductive outer coating or layer.Non-conductive plates, such as acrylic plates 12, may be provided with aconductive coating on at least the mold surface 18 and cavity surfacesto allow electrodeposition on the stacked laminate mold as follows. Sucha coating may be applied by any suitable known method, such as vaporcoating. One particular method of applying a silver coating is describedas follows.

The surfaces to be coated are first cleaned. Next, the surface issensitized by spraying with a suitable sensitizer, such as an acidifiedstannous chloride solution, for approximately one minute. One suchsolution can be prepared by combining 40 grams of stannous chloride, 10milliliters of con-hydrochloric acid, and 1 gallon of distilled water.The mold 10 is then rinsed with distilled water. A silver solution andreducer solution are then applied simultaneously with a dual nozzlespray gun. A suitable reducer can be made by combining 26 grams ofdextrose, 2.5 milliliters of formaldehyde, and 1 gallon of distilledwater. A suitable silver solution can be made by adding to 1 gallon ofdistilled water, in order: 10 grams potassium hydroxide; 50 millilitersammonium hydroxide; and 22.5 grams of silver nitrate. The mold is thenrinsed with distilled water is and ready for electrodeposition.

As discussed above, the stacked laminate mold may be used to mold anintermediate mold. The intermediate mold formed with stacked laminatemold 10 can be any desired material. In one preferred embodiment, anickel mold is formed from stacked laminate mold 10 by anelectrodeposition process. For the purposes of this invention, the term"electrodeposition" includes both "electrolytic" and "electroless"plating, which differ primarily in the source of the electrons used forreduction. In the preferred electrolytic embodiments, the electrons aresupplied by an external source, such as a direct current power supply,whereas in the electroless plating process the electrons are internallyprovided by a chemical reducing agent in the plating solution.

If the stacked laminate mold 10 comprises metal plates 12, thepreferably at least the mold surfaces 18 and the cavity surfaces of thestacked laminate mold 10 are passivated, such as by contacting thesurfaces with a 2% solution of potassium dichromate in distilled waterat room temperature. The mold 10 is then rinsed with distilled water.Passivation of the surfaces to be electroplated is desirable in that itprovides a thin oxide coating which facilitates removal of anelectroformed article from a metal mold 10. Passivation may not benecessary in the case where the mold 10 comprises non-conductive plates12 and is provided with a conductive coating as previously discussed. Inthis case the conductive layer is transferred from the mold 10 to theelectroformed article as hereinafter produced to facilitate removal ofthe electroplated article from the mold 10.

The mold 10 can then be immersed in a plating bath for a desired periodof time for the electrodeposition of a material on the surface of themold. Any appropriate eletrodepositable material may be used, such asnickel, copper, or alloys thereof.

In one embodiment of this invention, the plating bath consists of asolution of nickel sulfamate (16 oz. of Ni/gal.); nickel bromide (0.5oz./gal.); and boric acid (4.0 oz./gal.) in distilled water with aspecific gravity of 1.375-1.40. Anodes are provided in the form ofS-nickel pellets. The pellets are immersed in the plating bath andcarried in titanium baskets enclosed in polypropylene fabric anodebasket bags. The temperature of the plating bath is maintained at 120°F. and a pH of 3.8-4.0. Normally during operations, the pH of theplating bath rises. Therefore, the pH is periodically adjusted by theaddition of sulfamic acid. Evaporation loses are compensated for by theaddition of distilled water to maintain the desired specific gravity.The plating bath is continuously filtered, such as through a 5 micronfilter. The filtered output of the pump is preferably directed at themold 10 to provide fresh nickel ions. This also provides a desiredagitation to the electrodeposition solution. Electrodeposition shouldcontinue until the plated structure has enough thickness and strength tofacilitate removal from the stacked laminate mold. In one preferredembodiment, the nickel article is approximately 2.5 mm (0.1 in) thick.

The deposition of the nickel on the mold 10 is a function of the D.C.current applied, with 0.001 inch/hour of nickel deposited on a flatsurface at average current density rate of 20 amperes per square foot(ASF). However, the electrodeposited material may have a tendency toaccumulate at a faster rate in electrolytic deposition adjacent sharpchanges in the geometry of the mold 10, such as at the base 46 of thecavities.

After the nickel inverse of the stacked laminate mold is formed, it ispossible to modify the shapes of the protrusions extending from the baseof the nickel positive. For instance, the tops of all of the protrusionscan be machined off parallel to the plane of the base to create afrustum of whatever the original protrusion geometry was. For instance,where the protrusions in the nickel positive are pyramids, it ispossible to make frusto-pyramids by machining off all of the vertices ofthe pyramidal protrusions. It is also possible to truncate theprotrusions at some angle non-parallel to the base of the nickelpositive. These truncated protrusions or frusto-protrusions may be madein the final molded article itself, or may be made in this intermediatenickel positive. When the nickel positive is so modified, a subsequentnegative mold made from the nickel positive will then have cavities thatare the inverse of the protrusions on the modified nickel positive, andwill thus differ from the cavities in the initial stacked laminate mold10.

After the nickel positive is provided as described above, a negativemold can be molded from the nickel positive. An illustrative andnon-limiting list of suitable materials for the negative mold includesilicone, plastisol, and polypropylene. It is also possible to form asecond elctrodeposited article form the first one. In this case, it ispreferable to passivate the first article such as with a chromatepassivation, to facilitate removal of the second plated article from thefirst.

An embodiment of a silicone mold can be formed as follows. The nickelpositive is preferably heat treated in an air atmosphere at 400° F. for4 hours. Then, a dam is formed around the periphery of the nickelpositive described above, such that the uncured mold material can beheld adjacent the surface of the nickel positive having protrusionsmolded by the cavities in the stacked laminate mold.

The silicone negative is then molded as follows. First, Sylgard 184silicone elastomer available from Dow Coming Company, Midland, Mich., ismixed with Sylgard curing agent in a 10:1 ratio. Next, this mixture isstirred vigorously for 1 minute and the bottom and sides of the mixingbeaker are scraped. This mixture is then poured onto the surface of thenickel positive and contained by the dam. The nickel positive with thesilicone mixture thereon is placed in a vacuum chamber at 25 inches ofmercury for 15 minutes. The nickel positive with the silicone thereon isremoved from the vacuum chamber and placed for 30 minutes in an ovenheated to 400° F. The nickel positive with the silicone mixture thereonis removed from the oven and cooled by running cold water over it andthen dried with pressurized air. The cured silicone negative is thenremoved from the nickel positive.

An example of a polypropylene negative mold can be formed from a nickelpositive as follows. The nickel master is placed on a 3.2 mm (0.125 in)thick aluminum carrier plate of suitable size. A polypropylene extrudedfilm or pellets are then placed onto the surface of the nickel tool. Abrass plate which has been chrome-plated and polished and having athickness of 0.8 mm (0.031 in) is then placed on the polypropylenematerial. A second aluminum carrier plate which is 3.2 mm (0.125 in)thick is then placed on the brass plate. This stacked assembly is thenplaced between the platens of a compression molding press that has beenpreheated to 350° F. One suitable press is a Wabash Hydraulic MoldingPress Model V75H-24-CLX, 75-ton compression capacity molding machine,available from Wabash, MPI, of Wabash, Ind. After approximately fiveminutes, a force of 150 psi is applied to the stacked assembly and heldfor a period of five minutes. A force of 500 psi is then applied forseven minutes to the stacked assembly. The heated stacked assembly isthen cooled to 180° F. while maintained under the pressure of 500 psi.The pressure is then removed from the stacked assembly and the stackedassembly is removed from the press. The top carrier plate and brassplate are then removed from the stacked assembly, and the moldedpolypropylene material is then removed from the nickel positive.

It is possible to use the molds described herein to mold an articlehaving different regions or groups. Each region can contain a group oflike cavities or protrusions, with the cavities or protrusions differingfrom region to region. Such differences can be in cavity or protrusionsize, configuration, and/or orientation. It is possible to combineportions of different intermediate molds such as the nickel mold orsilicone molds described herein to mold such articles. It is alsopossible to combine portions of different final molded articles toachieve molded articles with the above-described regions or groups.

The present invention has now been described with reference to severalembodiments thereof. The foregoing detailed description and exampleshave been given for clarity of understanding only. No unnecessarylimitations are to be understood therefrom. It will be apparent to thoseskilled in the art that many changes can be made in the embodimentsdescribed without departing from the scope of the invention. Thus, thescope of the present invention should not be limited to the exactdetails and structures described herein, but rather by the structuresdescribed by the language of the claims, and the equivalents of thosestructures.

What is claimed is:
 1. A method of forming a stacked laminate moldcomprising the steps of:a) orienting a plurality of plates to have theirrespective major planes at a first angle relative to a fixed referenceplane and parallel to one another, each of the plates including opposedparallel first and second major surfaces defining therebetween the majorplane of each of the plurality of plates, each of the plates furtherincluding a mold surface connecting the first and second major surfaces;b) forming a groove in each plate of the plurality of plates, the grooveincluding a groove surface defined by a cylindric surface that is theconstruct of translating a two-dimensional groove profile through theplate along a line that is oblique to at least one of the plate majorsurface and the plate mold surface, and wherein the groove surfaceintersects each respective plate first major surface and each respectiveplate mold surface; and thereafter c) reorienting the plates to havetheir respective major planes at a second angle relative to thereference for molding.
 2. The method of claim 1, wherein the moldsurfaces of the plurality of plates are coplanar upon performing stepc).
 3. The method of claim 1, wherein step b) comprises forming a grooveincluding a planar first groove surface, a planar second groove surface,and a base joining the first and second groove surfaces, wherein thefirst groove surface intersects each respective plate first majorsurface and each respective plate mold surface, wherein the secondgroove surface intersects each respective plate first major surface andeach respective plate mold surface, and wherein the base is obliquerelative to at least one of the major plane and the mold surface.
 4. Themethod of claim 1, wherein step b) comprises inducing relative motionbetween the plurality of plates and a cutting tool.
 5. The method ofclaim 1, wherein the groove surface is defined by a cylindric surfacethat is the construct of translating the two-dimensional groove profilethrough the plate along a line that is oblique to the major plane of theplate.
 6. The method of claim 1, wherein step b) comprises forming aplurality of grooves in each plate of the plurality of plates.
 7. Themethod of claim 6, comprising the further step ofd) moving a first oneof the plurality of plates relative to a second and a third plate eachadjacent the first plate, such that a cavity in the first plate formedby a first of the plurality of grooves is offset from cavities formed bythe first groove in the second and third plates.
 8. The method of claim7, wherein:each of the plates further comprises opposed first and secondends joining the first and second major surfaces; and the plurality ofplates comprises a first plurality of plates having a first lengthmeasured from the first end to the second end, and a second plurality ofplates having a second length measured from the first end to the secondend, the second length being greater than the first length; the methodcomprising the further steps of:a') prior to step b), aligning the firstand second pluralities of plates such that each of the plate first endsis coplanar; and b') subsequent to step b), aligning the first andsecond pluralities of plates such that each of the plate second ends iscoplanar.
 9. The method of claim 1, including the further step of:d)subsequent to step b), inserting a plurality of spacers into the moldsuch that a respective one of the plurality of spacers is adjacent arespective one of the plurality of plates, wherein each respectivespacer overlays at least that portion of the first major surface of eachrespective plate intersected by the groove surface.
 10. A stackedlaminate mold, comprising:a plurality of plates, each of said platesincluding:opposed parallel first and second planar major surfacesdefining therebetween a major plane of each of said plurality of plates;a mold surface connecting said first and second major surfaces; and aplurality of cavities in each of the plurality of plates, wherein eachof the cavities is open at least to said mold surface and includes acavity surface defined by a cylindric surface that is the construct oftranslating a two-dimensional cavity profile through said plate along aline that is oblique to at least one of said plate major surface andsaid plate mold surface, and wherein said cavity surface intersects eachrespective plate first major surface and each respective plate moldsurface; wherein said first major surface of a first one of theplurality of plates is adjacent said second major surface of a secondone of said plurality of plates.
 11. The mold of claim 10, wherein saidmold surfaces of each of said plurality of plates are coplanar.
 12. Themold of claim 10, wherein said cavity surface includes a planar firstcavity surface, a planar second cavity surface, and a base joining saidfirst and second cavity surfaces, wherein said first cavity surfaceintersects each respective plate first major surface and each respectiveplate mold surface, wherein said second cavity surface intersects eachrespective plate first major surface and each respective plate moldsurface, and wherein said base is oblique relative to at least one ofsaid major plane and said mold surface.
 13. The mold of claim 10,wherein said cavity surface is defined by a cylindric surface that isthe construct of translating said two-dimensional cavity profile throughsaid plate along a line that is oblique to said major plane of said,plate.
 14. The mold of claim 10, wherein each of said mold cavities areopen at said mold surface of said plates and are bounded at least by:i)said cavity surface; and ii) said second major surface of a second oneof said plurality of plates adjacent to said first major surface of saidfirst plate.
 15. The mold of claim 12, wherein each of said moldcavities are open at said mold surface of said plates and being boundedat least by:i) said first cavity surface in a first one of saidplurality of plates; ii) said second cavity surface in said first plate;iii) said cavity base in said first plate; and iv) said second majorsurface of a second one of said plurality of plates adjacent to saidfirst major surface of said first plate.
 16. The mold of claim 10,further comprising a plurality of spacers wherein a respective one ofsaid plurality of spacers is adjacent a respective one of said pluralityof plates, wherein each respective spacer overlays at least that portionof said first major surface of each respective plate intersected by saidcavity surface.